Mechanics 1 potiential energy

2 A block of mass is placed on a rough horizontal table. A string attached to the block runs horizontally to the edge of the table, passes round a smooth peg, and supports a sphere of mass attached to its other end. The motion of the block on the table is resisted by a frictional force of magnitude , where . The system is initally at rest.
a) Show that when the block and the sphere have each moved a distance , their common speed is given by
b) Show that the total energy lost by the sphere as it falls through the distance is

c) Write down an expression for the energy gained by the block as it moves through the distance h use your answer to check the expression for the tension which you found in part (b)Answer Now I can manage part a: , so . This is easy enough to rearrange to make the subject and get the expression in part a).